Method for operating a motor vehicle with hybrid drive including an internal combustion engine and an electric machine with associated energy storage, which is chargeable when the electric machine is operated as generator, and an electronically shiftable transmission whose gears are manually shiftable up and down by actuating a selector element.
Motor vehicles with hybrid drive become increasingly popular. Especially so-called full hybrid vehicles whose energy storage, i.e., whose battery is exclusively charged via the electric machine that is operated as generator, and so-called plug-in hybrid vehicles, which in addition offer the possibility to charge the energy storage via a conventional electric outlet connection. Both have in common that they are configured so that on one hand a hybrid operating mode and a purely electric operating mode exist. In the hybrid mode the internal combustion engine is predominantly active, while the electric machine, which is then operated as electric motor, can have a supportive drive function, and can for example contribute an additional acceleration (boosting) or serve for lowering the load point. As an alternative the electric machine can be operated as generator in the hybrid mode and can either recuperate, i.e., charge the energy storage (traction battery), or it can increase the load point of the internal combustion engine. While the traction battery can thus be recharged when driving in the generator mode, the traction battery is predominantly discharged in the purely electric operating mode.
Especially in plug-in-hybrid-vehicles that have a relatively large energy storage, the purely electric operating mode is mostly selected as default state after entering and activating the vehicle, i.e., after starting the drive the vehicle is driven predominantly electrically until the energy storage is empty. In order to offer the option to the driver to quickly charge the energy storage via the internal combustion engine during the drive, a charge mode can be selected as special form of the hybrid operating mode. In this charge mode, in which the electric machine is then operated as generator, the internal combustion engine participates in driving the electric machine in all weak and partial load phases; a certain increase of the load point occurs. The charge mode is selected by the driver, i.e., either by actuating a separate operating button, which is only provided for this purpose, or by selecting a menu item in an input menu on a display.
This type of selecting the charge mode, however, requires the installation and actuation of an additional button in the vehicle, which leads to increased costs and may be uncomfortable for the driver. Also the selection of an additional menu item in an input menu that has to be configured is cumbersome, and may render the input menu overly complex or hard to comprehend.